Terrot MT 1, 100cc 2 stroke: non-starter!

[iansoady]

The amount of time you (and everyone else!) have spent on this, you'd have been better stripping the whole thing and checking crankshaft seals etc. It'll only take an hour at the most to have it reduced to its kit form.

You do seem to be clutching at straws....

[Terrotmt1]

Totally agree.
I am wasting everyone's time now.

I changed the condenser to the new one. Sparks with the plug out.
Set the timing etc and kicked the thing and me to death. My right foot hurts.

Absolutely nothing.

Changed the carb from Villiers to Big Chinese, nothing. Foot hurts more.
Plug is not wet despite all the choke/none choke and all the other combinations.

It is coming out, it will be stripped and I'll take the piston/cylinder to V Services for their assessment.
I will convert the crank cases to single or double lip seals and start all over again.

 Packing up trying to get this done as it is.
Thank you for everyone's time and efforts. Be glad it's not yours.

See you all soon!

It will take a lot longer than 1 hour.....

[Terrotmt1]

Engine out, took 1 hour!
Engine apart, 45 mins.
The felt seal is out. It is in a steel base so can be readily swopped for a double lip seal. The fit of the felt is surprisingly tight to the crank shaft so I think was a good seal (pressure -wise)
It has a fine spring on the crank side like a lip seal has, but it is very loose and seems to do nothing.

The crank ball bearings will be changed for new.

The 'brass-bush' on the mag side is the problem. There is not much casting to machine a counter bore for a double or maybe single lip seal, so I need to find out what sizes are available.
Here are some pics of the parts. The crank is 17mm Dia.
I will take expert advice on the barrel and piston! I can only get standard size pistons (48.5mm dia) which is the same size as mine.

[chaterlea25]

Hi Terrot,
Am I seeing things or dreaming ?
The port in the centre of the photo above looks almost blocked??

As to sealing the crankcase, one or two possibilities
Some re machining of the magneto side case to add a thick disc fixed to the machined up face by some screws/sealant, the disc would house a normal lipped seal

There are companies like this one (that's local to me) who can produce special seals that would fit instead of the bronze scroll, https://www.youtube.com/watch?v=0aiJMD6eYOQ
The special seals are very reasonably priced, I got some made to keep the gear oil from flowing into the clutch
on a couple of Indian Chief's, I seem to remember the smallest "section" seal is 3-4 mm

Or fit a double rubber sealed bearing on that side??? leave the seals in place

John

[Terrotmt1]

Thank you John.
The ports are all clear, I was trying to show the condition of the bore.
As to seals, at Simply Bearings I've found the correct bearings and a double lip seal to size for the clutch side.
The mag side has that brass bush, but again found a lip seal that will fit if I get some or all of the brass sleeve machined out.
This side, the seal can go outboard of the bearing.
Total cost of parts about £10!
Need to find a small machine shop now.

Feeling very positive about this lot.

[The Artful Bodger]

Out of curiosity (that wot killed the cat) is there a felt seal on the plain bush side? If not it would rely on the bush / crank fit to be very good. My M/Debon (admittedly somewhat older than yours) has plain bushes both sides and no seals. Obviously a ball or roller bearing would need a seal hence the felt on that side.
  If there is no seal on the plain bush side it would suggest wear in the bush (and or the crank) so a new bush would be needed and if necessary the crank ground that side. If this is the case, and you feel the felt is a good fit, then by doing the bush the engine would still be standard and shouldn't require machining to fit other oil seals.
  Small Villiers engines have a bronze sealing ring which is pushed against a facing surface with a spring, I would assume your spring should be pushing a washer of some sort against the felt seal to keep it compressed against the crank. A simple but effective system which personally I would prefer to leave in place rather than fit a lipped seal, however your bike so your choice.
  If there is sufficient wear in the bronze bush even if you did fit a seal there's a possibility that the crank rattling a little in the bush could still cause a leak that side with a seal fitted.
  I had a bearing develop play on the timing side of one of my Banatams, I had to change it not due to vibration or noise but because oil / petrol was leaking out and onto the points. The seals were relatively new it was the small amount of play in the bearing allowing the crank to move and the seal to leak.
   As already mentioned, strange looking sight with the ports?

Colin

[mini-me]

I agree those ports look bunged up.

chuck it into a bucket of hot caustic soda and see what its like after.

[Terrotmt1]

When I first did this engine everything was soaked in paraffin to soften the carbon etc and I have poked every portion the barrel.
The picture shows the bore but also the coarse sand casting grain in the casting of the port.
All the ports look the same.

There was no felt seal on the magneto bush side, the exploded drawings of the engine so nothing either.
The fit or clearance of the bush to the crank is very close, but there is no contact due to the ball bearing.
All the bearings are original!
I will be fitting new ones and will fit a lip seal on the mag side.

At least this way the bottom end should be tight.
I'm trying to think of a way to test the lower crank under pressure but the con rod projects about 30 mm above the face where the barrel mounts so can't put a flat plate over the cease top and add a pressure inlet.

[john.k]

before damaging the bush,check clearance,it may be ok,and will save a lot of work....Next,make sure the crank isnt bent,often happens with taper flywheels etc.....If the bush needs replacing,it will have to be line reamed with a piloted reamer in the drive side.....I notice an oil spiral,make sure any new bush doesnt have the spiral cut too close to the ends...To check compression,I would simply fit piston and barrel,and check for the puff of air coming up the transfer port,usually a "pop" too.Dont forget to oil the bush for a seal.....Crankcase compression will be low with a "mower type" crank,not a full circle one.Regards.

[cardan]

There is something seriously wrong with those ports! Manufacturing problem? The whole idea of the two-stroke engine is that the piston rings control the port opening and closing with some precision. That ain't going to happen here. A small engine re-conditioner - if there are still such places - will advise.

Re the magneto-side shaft and bush. A bush is fine to act as both bearing and seal, but it wouldn't usually have an oil spiral; at least make sure it doesn't run all the way through the bush. The shaft needs to be round, unworn (not smaller diameter than the outer end!) and straight, and the fit in the bush pretty neat - maybe only a thou or so.

Cheers

Leon

[mini-me]

Its ironic that with all your obsession with ignition timing it may well be the port timing that is the problem?

Maybe that its a Dud replacement part has been fitted somewhere along the line and the damn thing never run since?


The paraffin soak is not up to clearing really hard old carbon, but that looks like metal in those ports.

[iansoady]

A small engine re-conditioner - if there are still such places - will advise.

I had my Ariel Arrow rebored by a company called Nametab in Redditch. The owner, Simon Bateman, was very knowledgeable about 2 strokes. If they're local to you maybe worth a visit?

http://www.nametabengineering.com/

[Terrotmt1]

I know Nametab, Villiers specialists. I used Simon when I needed parts for a Villiers (E I rebuilt (but never started) on a Barlotti Kart I restored.
He has down-sized to racing only work, the spares went to my new friends, Villiers Services. I have a 2 stroke specialist (Reed Speed) and VS quite close, but I'll try VS and see what they say.
They have an engine cleaning service.

Back to the barrel; this morning I grazed a scriber down everywhere and all are clear, ie no coke. When I originally stripped the engine there was 3mm of coke in the exhaust port, the down pipe and the silencer. This is why I replaced the pipe and silencer.
I have shone a high intensity torch light through the ports to, a stiff bottle brush and a gallon of paraffin. I will go through the lot again.

This is why I have taken it all down again to start a fresh build.

The bearings and seals are on their way. I have managed to get a double lip seal of 17mm x 22mmOD. This means I can remove just 5mm of the brass 'grooved' sleeve next to the crank bearing and a touch of the case casting so preserving the majority of the bush, but I think the bush is not 1 thou clear of the crank, much more like 5 or 10 thou,
When done I will have new bearings, 2 x double lip seals on the crankshaft so the bottom should be air tight.

I will drill an M6 hole in the bottom of one case half to allow a petrol drain (as per Colin's Bantam) with a tight plug.
Will have to make all new paper gaskets as they all tore when I took it apart.

After this will be the piston/barrel check. With no oversize piston to be found I think I'm lumbered to what I have....

I noticed the head gaskets had not leaked, no oil residue on the top fin.
Have to wait now for the parts, but will do the gaskets tomorrow in preparation or prob go to Villiers Services as well.

[mini-me]

In that case whats going on in those ports? because they don't look at all good to me.

Whats the bore diameter? is it per spec sheet? It would not surprise me if its been bored out too far or maybe even a cylinder for something smaller has been bored out.

I have seen examples of 1950s French peasant bodgery, nothing is beyond them. I am convinced that is likely where your problem is; teh bike was never manufactured to space age tolerances, and its well known that two strokes run best when knackered.
Can you not send a pic to the Terrot club of those ports? Or maybe one of the dealers you have bought from for an opinion?

I did a bit of search on ebay france, found this cylinder with good shot of the ports, not the same as yours exactly but just look at the finish of those ports

https://www.ebay.fr/itm/cylindre-rond-moto-collection-TERROT-250-magnat-debon/202280803129?hash=item2f18e01b39:g:WkQAAOSwn-tZLEiT

[The Artful Bodger]

I would be very concerned with 5-10 thou clearance with the bush, if you can't check it yourself maybe take it to an engineering shop and have them see what's what. No mains bush should be near that much and you're asking a lot for an oil seal to seal with that much potential crank movement.
  I believe you mentioned you have a lathe, it's not a difficult job to turn up a new mains bush. If you have a lathe you must have a micrometer so you can check the crank for uneven wear and ovality, yourself. I made a tool post grinder for my lathe and ground my M/D crank myself, bought some lead bronze off eBay to make the new bushes (softer bronze as the shafts aren't super hard). The oil scrolls I will do freehand with a pencil die grinder. Worse case scenario it shouldn't cost a fortune for one main journal to be ground by a machine shop, just ask them to remove the bare minimum to clean it up and make the bush to suit.
  With the bush fitting the crank correctly an oil seal shouldn't be needed and the engine should be a lot smoother. Got to be worth getting everything right while the engine's down.
  Like the others I'm suspicious about those ports, old carbon can be like concrete. I would try attacking them with something serious until I was sure they were definitely solid metal.

Colin